A common practice in forming fibers of mineral material is to pass material in a molten state through the orifices of the peripheral wall of a centrifuge or spinner to create primary fibers. Thereafter, the primary fibers are further attenuated into a veil of secondary fibers of smaller diameter by the action of a flow of gases discharged downwardly from a blower. It is known in the prior art that such blowers can be annular in shape and can be adapted to blow air, steam or other gases. It is also known in the prior art that the air drag attenuation provided to the primary fibers by the flow of gases from the blower can be greatly increased by creating some turbulence in the flow of gases. The air drag attenuation can also be increased by inducing a flow of air to pass over the top of the blower and intermediate the blower and the spinner peripheral wall. The combination of the flow of gases from the blower and the induced air attenuates the primary fibers into secondary fibers and cools and quenches the fibers, causing them to break into finite lengths.
One of the problems associated with the blowers of the fiber-forming devices of the prior art is that such blowers consume large amounts of energy. Improvements to fiber-forming devices which increase the amount of induced air or facilitate a reduction in the amount of energy required by the blower are needed. Another problem of the prior art devices is that the heat from the burner causes excessive deterioration of the blower discharge port. An additional problem with the devices of the prior art is that the fiber veils are unsteady and exhibit some fiber clumping.
The present invention is directed toward a fiber-forming apparatus which greatly increases the amount of air induced by the blower, and which may reduce the amount of energy which must be expended by the blower in the fiberizing process. The present invention also substantially reduces deterioration of the blower discharge port by positioning the discharge port so as to be subject to less heat from the burner than is common with the blowers of the prior art. Also, the fiber forming apparatus of the present invention produces a more steady fiber veil exhibiting a lack of fiber roping or clumping.